This invention relates to novel microfiber-containing yarns and fabrics formed therefrom. More particularly, this invention relates to novel core-spun yarns and fabrics made from such yarns wherein the core-spun yarns contain a microfiber element.
Microfibers are very thin fibers having a linear density of less than 1 denier per filament (dpf), making these fibers even finer than silk, which has a linear density of 1 dpf. Microfibers, also known as "microdenier fibers", have silk-like properties, including the drape, flow, look, feel, movement, softness and luxuriousness of silk, which make the microfibers desirable in the fashion industry for making items such as intimate apparel, outerwear, and sportswear. Although similar to silk, synthetic microfibers also have the useful properties and performance imparted to and in common with certain man-made fibers. For example, synthetic microfibers tend to be easy to care for and often have "wash & wear" capability.
Microfibers are typically formed from composite fibers by processes well known in the art. Composite fibers are manufactured in general by combining at least two fiber-forming polymers via extrusion. Microfibers can be formed from such composite fibers by dissolving one of the polymer components from the composite fibers.
U.S. Pat. No. 3,700,545 discloses a multi-segmented (i.e., multilayered) polyester or polyamide fiber having at least 10 fine segments (layers) with cross sectional shapes and areas irregular and uneven to each other. The spun fibers are treated with an alkali or an acid to decompose and remove at least a part of the polyester or polyamide. Also described therein is a complex spinneret for the manufacture of such fibers.
U.S. Pat. No. 3,382,305 discloses a process for the formation of microfibers having an average diameter of 0.01 to 3 microns by blending two incompatible polymers and extruding the resultant mixture into filaments and further dissolving one of the polymers from the filament.
U.S. Pat. No. 5,120,598 describes ultra-fine polymeric fibers for cleaning up oil spills. The fibers were produced by mixing a polyolefin with poly(vinyl alcohol) and extruding the mixture through a die followed by further orientation. The poly(vinyl alcohol) is extracted with water to yield ultra-fine polymeric fibers.
EP-A-0,498,672 discloses microfiber-generating fibers of island-in-the-sea type obtained by melt extrusion of a mixture of two polymers, whereby the sea polymer is soluble in a solvent and releases the insoluble island fiber of a fineness of 0.01 denier or less. Described is poly(vinyl) alcohol as the sea polymer.
U.S. Pat. No. 4,233,355 discloses a separable unitary composite fiber comprised of a polyester or polyamide which is insoluble in a given solvent and a copolyester of ethylene terephthalate units and ethylene 5-sodium sulfoisophthalate units, which is soluble in a given solvent. The composite fiber was treated with an aqueous alkaline solution to dissolve out at least part of the soluble polymer component to yield fine fibers. The cross sectional views of the composite fibers show an "islands-in-the-sea" type, where the "islands" are the fine fibers of the insoluble polymer surrounded by the "sea" of the soluble polymer. The highest described number of segments or "islands" are 14 and the lowest described fineness were 108 filaments having a total fineness of 70 denier which corresponds to 0.65 denier per filament.
A particularly useful process of forming microfibers is disclosed in copending, commonly assigned U.S. Patent application Ser. No. 08/040,715 (filed Mar. 31, 1993), now U.S. Pat. No. 5,366,804 which will be more fully described hereinbelow and which solves underlying problems associated with previous known processes of forming microfibers.
Fabrics which are composed of microfiber yarns, whether formed completely from microfiber yarns or from a blend of 100% microfiber yarns and additional yarns, are expensive, primarily because the processes for making the microfibers and yarns are highly specialized and generate a relatively large amount of waste. In addition, fabrics made entirely of microfiber yarn will have limited use in applications requiring properties beyond those provided by the microfiber yarn. For example, processing conditions used in making microfibers can result in microfibers having low shrinkage. Fabrics made entirely of such low shrinkage microfibers cannot be used in applications requiring fabrics having high shrinkage as well as silk-like and wash-and-wear properties. Fabrics made entirely of low shrinkage microfibers are also generally unsuitable for use in sportswear or heavyweight apparel, e.g., pants and uniforms, which should feel soft like cotton but have greater strength than is generally provided by a microfiber yarn.
In making fabrics having two conflicting properties, e.g., softness and high strength, it is desirable to have sheath/core configuration yarns so that the fabric has the feel imparted by one fiber but the strength imparted by another. Core-spun yarns having a distinct sheath/core structure with different fibers in the core and in the sheath and possessing most of the advantageous properties of both the core and sheath fibers are known in the art. Reference is made, for example, to U.S. Pat. Nos. 3,828,544 to Alker and 4,711,079 to Newton et al.
Prior to the present invention, however, it has not been suggested to use microfibers or microfiber-generating fibers in either the sheath or the core of core-spun yarns nor how to incorporate the highly specialized microfiber-manufacturing process into a core-spinning process to form a core-spun yarn and fabric therefrom without sacrificing the excellent properties imparted by the microfibers.
Accordingly, it is a primary object of this invention to provide a microfiber-containing yarn which has advantageous properties in addition to those properties generally associated with 100% microfiber yarns.
It is another object of this invention to provide a less expensive microfiber-containing yarn without substantially sacrificing the excellent properties associated with 100% microfiber yarns.
It is a further object to provide a fabric made from a microfiber-containing yarn having the characteristics set forth in the foregoing objects.
These and other objects which are achieved according to the present invention can be discerned from the foregoing description.